Inductive sensors are used in rotary encoders, for example, to determine the angular position of two machine components that are able to be rotated relative to one another. They are also used in measuring devices to determine the position of two machine components that may be displaced longitudinally relative to one another.
In the case of inductive sensors, excitation coils and receiver coils are often applied onto a shared circuit board in the form of circuit traces, the circuit board being permanently connected to a stator of a rotary encoder, for instance. Situated across from this circuit board is another board onto which electrically conductive areas are applied as a pitch structure at periodic intervals, and which are connected to the rotor of the rotary encoder in a rotatably fixed manner. When an electric excitation field is applied to the excitation coils, signals as a function of the angular position are generated in the receiving coils, the signals being generated during the relative turning of rotor and stator. These signals are then processed further in evaluation electronics. The components of such an evaluation electronics are often accommodated on an additional circuit board. The circuit board having the excitation and receiver coils and the circuit board having the evaluation electronics are quite often interconnected via flex conductors and plug-in connections. This type of electrical connection takes up a relatively large volume. However, this runs counter to the constant call for miniaturization of such sensors or rotary encoders.
German Published Patent Application No. 101 11 966 describes a structure for an inductive sensor in which the excitation and receiver coils and also components of the evaluation electronics are implemented in a multi-layer structure in the form of a laminate. This structure has the disadvantage, however, that it may be relatively sensitive to external influences and may not allow optimum space utilization.
It is an aspect of the present invention to provide an inductive sensor that may stand up to external influences and may require extremely limited installation space. The present invention may also provide a reliable rotary encoder having small outer dimensions.